In the semiconductor industry semiconductor chips such as microprocessors and the like are packaged on carriers called matrix trays. The matrix trays carry a number of semiconductor chips which are passed along a production line for assembly of completed circuit boards. The matrix trays are typically injection moulded plastics having a height of about 1 cm.
The trays carry technical information relevant to the tray, the chips carried or the process, such as temperature rating, part number, date code, etc. This technical information is usually embossed on the edge of the trays, which is typically about 1 cm high. As the trays flow through the production line the following inconveniences occur:    1. Difficulty in reading the embossed descriptions on tray surfaces, especially when they are stacked high. The printed information is not large enough due to the limited space on the edge of the tray. Also, the printed characters and numbers are the same colour as the tray's surfaces so there is little contrast to aid in reading them.    2. Difficulty in identifying trays that house good chips as against those used to store rejected ones. When bad chips are identified and segregated by the machines during the assembly process, they are separated but housed onto the same type of trays. The same type of trays are needed as they are specifically designed to house a particular size and family type of chips.    3. Difficulty in identifying different types of chips within a family that use the same body dimension of the tray. As different machines are required for handling a particular type of chip within a family, the use of the common tray makes it difficult to identify the correct chips for each machine.    4. Difficulty in identifying the correct tray orientation during the machine loading. The tray must be loaded manually with a specific orientation. Although present trays come with a tiny corner chamfer on one of its corners, it is not conspicuous enough to ensure correct loading onto the machine.
It has been proposed to use coloured stickers to help differentiate certain trays from others. However, the stickers need to be removed before delivery to customers and this sometimes leaves adhesive material on the tray.